GO:0051497 negative regulation of stress fiber assembly: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0051497 describes any process that stops, prevents, or reduces the assembly of stress fibers, which are contractile bundles of actin microfilaments and associated proteins found in fibroblasts.
• Stress fiber assembly is driven by Rho GTPase signaling, and negative regulation of this process often involves suppression of RhoA activity or downstream effectors.
• Rac1 GTPase is critical for actin stress fiber formation and focal adhesion assembly, so negative regulators of Rac1 can inhibit stress fiber assembly.
• Dysregulated stress fiber assembly contributes to fibrosis, and morphological reprogramming of primary cilia can mitigate fibrotic phenotypes in fibroblasts.
• Septins and class 18 myosins modulate actin cytoskeleton organization, including stress fiber dynamics, in endothelial and other cell types.
• Research on GO:0051497 uses CRISPR knockout, point mutation, knock-in, overexpression models, plus imaging, proteomics, and transcriptomics to dissect regulatory mechanisms.
Description
Stress fibers are contractile actin bundles that provide mechanical support and drive cell shape changes, adhesion, and motility in fibroblasts and other cells. The assembly of stress fibers is a highly regulated process, and its negative regulation—captured by the Gene Ontology term GO:0051497—is essential for maintaining normal cytoskeletal architecture and preventing pathological states such as fibrosis. Understanding how cells stop or reduce stress fiber assembly is critical for researchers studying cell mechanics, wound healing, and fibrotic diseases. This article synthesizes authoritative QuickGO data and verified PubMed literature to explain the mechanisms, key genes, and experimental approaches for studying negative regulation of stress fiber assembly.
negative regulation of stress fiber assembly At A Glance
| GO ID | GO:0051497 |
|---|---|
| GO term | negative regulation of stress fiber assembly |
| Ontology | biological_process |
| Synonym | down regulation of stress fiber formation; down-regulation of stress fiber formation; downregulation of stress fiber formation; inhibition of stress fiber formation; negative regulation of stress fibre biosynthesis; negative regulation of stress fibre formation |
| Major function | Stops, prevents, or reduces the assembly of stress fibers, contractile bundles of actin microfilaments and associated proteins in fibroblasts. |
| Related cellular component | Stress fibers, focal adhesions, actin cytoskeleton. |
| Key regulators | Rho GTPase, Rac1 GTPase, G protein beta/gamma subunits, septins, class 18 myosins. |
| Associated disease relevance | Fibrosis, impaired wound healing, and cytoskeletal disorders. |
What Is GO:0051497?
GO:0051497, negative regulation of stress fiber assembly, is defined as any biological process that stops, prevents, or reduces the frequency, rate, or extent of the assembly of a stress fiber, which is a bundle of microfilaments and other proteins found in fibroblasts. This term encompasses molecular events that inhibit the formation of these contractile actin structures, including suppression of Rho GTPase signaling, inhibition of actin polymerization, and disruption of focal adhesion complexes that anchor stress fibers.
Why Is negative regulation of stress fiber assembly Important in Cell Biology?
Negative regulation of stress fiber assembly is crucial for preventing excessive contractility and pathological tissue remodeling. In fibroblasts, uncontrolled stress fiber formation contributes to fibrosis, and interventions that reduce stress fiber assembly can mitigate fibrotic phenotypes. Moreover, proper regulation of stress fibers is essential for cell migration, adhesion, and mechanotransduction, processes that are hijacked in cancer and chronic inflammatory diseases. Studying GO:0051497 provides insights into how cells maintain cytoskeletal homeostasis and offers therapeutic targets for fibrotic disorders.
• Prevents excessive fibrosis by limiting stress fiber assembly in fibroblasts.
• Regulates cell migration and adhesion dynamics through Rho GTPase and Rac1 signaling.
• Maintains endothelial monolayer integrity via septin and actin interactions.
• Modulates sarcomeric and non-muscle actin organization through class 18 myosins.
• Impacts wound healing and tissue repair by controlling contractile forces.
• Influences cancer cell invasion and metastasis by altering cytoskeletal architecture.
• Provides targets for anti-fibrotic therapies.
• Helps understand mechanotransduction in fibroblasts and myofibroblasts.
• Relevant to developmental processes where stress fibers guide morphogenesis.
• Offers biomarkers for cytoskeletal disorders and fibrotic conditions.
What Happens During negative regulation of stress fiber assembly?
Inhibition of Rho GTPase signaling
In simple terms: Turning off the molecular switch that builds stress fibers.
Stress fiber assembly is driven by Rho GTPase, which activates downstream effectors such as ROCK to promote actin polymerization and myosin contractility. Negative regulation of stress fiber assembly often involves suppressing RhoA activity or its downstream signaling. For example, G protein beta/gamma subunits can induce stress fiber formation in a Rho-dependent manner, and blocking this pathway reduces assembly. In corneal fibroblasts and myofibroblasts, Rho-mediated assembly is differentially regulated, suggesting cell-type-specific inhibitory mechanisms.
Suppression of Rac1-mediated actin polymerization
In simple terms: Stopping Rac1 from helping actin filaments bundle together.
Rac1 GTPase is critical for actin stress fiber formation and focal adhesion complex assembly. Genetic deletion of Rac1 impairs stress fiber formation, indicating that negative regulators of Rac1 can inhibit this process. Thus, negative regulation of stress fiber assembly may involve proteins that downregulate Rac1 activity or its effectors, preventing actin bundling and focal adhesion maturation.
Disassembly of focal adhesions
In simple terms: Loosening the anchors that hold stress fibers in place.
Stress fibers are anchored to focal adhesions, which are multiprotein complexes that link the actin cytoskeleton to the extracellular matrix. Negative regulation of stress fiber assembly can occur through disassembly of focal adhesions, which destabilizes stress fibers. Rac1 deletion disrupts focal adhesion assembly, and Rho signaling is required for focal adhesion maturation. Therefore, processes that promote focal adhesion disassembly indirectly inhibit stress fiber assembly.
Modulation by septins and myosins
In simple terms: Other cytoskeletal proteins that can block stress fiber formation.
Septins contribute to endothelial cell-cell junctions and monolayer integrity, and they interact with actin to regulate stress fiber dynamics. Class 18 myosins, Myo18A and Myo18B, are specialist sarcomeric proteins that can influence actin organization, including stress fibers. Negative regulation of stress fiber assembly may involve these proteins sequestering actin monomers or competing with actin-crosslinking proteins, thereby reducing stress fiber formation.
Morphological reprogramming of primary cilia
In simple terms: Changing cilia length to reduce fibrosis and stress fibers.
Morphological reprogramming of primary cilia length mitigates the fibrotic phenotype in fibroblasts across diverse fibrotic conditions. This reprogramming is associated with reduced stress fiber assembly, suggesting that primary cilia signaling can negatively regulate stress fiber formation. The mechanism may involve ciliary-dependent changes in Rho GTPase activity or actin-binding proteins.
Key Genes Involved in GO:0051497 negative regulation of stress fiber assembly
The following genes and proteins are experimentally implicated in the regulation of stress fiber assembly, including negative regulation of this process.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RHOA | Rho GTPase that promotes stress fiber assembly; its inhibition negatively regulates assembly. | Target for anti-fibrotic therapies; knockout reduces stress fibers. |
| RAC1 | GTPase critical for actin stress fiber formation and focal adhesion assembly; negative regulators suppress its activity. | Genetic deletion impairs stress fiber formation; model for cytoskeletal studies. |
| GNAI | G protein beta/gamma subunits induce stress fiber formation in a Rho-dependent manner. | Modulating G protein signaling can inhibit stress fiber assembly. |
| SEPT2 | Septin involved in endothelial cell-cell junctions and actin dynamics. | Knockdown alters stress fiber organization and monolayer integrity. |
| SEPT7 | Septin that contributes to actin cytoskeleton regulation. | Potential negative regulator of stress fiber assembly in endothelial cells. |
| MYO18A | Class 18 myosin with roles in actin organization. | May compete with stress fiber assembly; knockout studies needed. |
| MYO18B | Class 18 myosin, specialist sarcomeric protein. | Implicated in actin bundle regulation; relevant to stress fiber dynamics. |
| ACTB | Beta-actin, major component of stress fibers. | Mutations affect stress fiber stability; target for knockout. |
| ACTG1 | Gamma-actin, component of stress fibers. | Overexpression can alter stress fiber assembly. |
| VCL | Vinculin, focal adhesion protein that anchors stress fibers. | Knockout disrupts focal adhesions and stress fibers. |
| PXN | Paxillin, focal adhesion component. | Phosphorylation regulates focal adhesion turnover and stress fiber assembly. |
| ZYX | Zyxin, stress fiber-associated protein. | Modulates actin bundling; potential negative regulator. |
| ROCK1 | Rho kinase, effector of RhoA that promotes stress fiber assembly. | Inhibition reduces stress fibers; target for negative regulation studies. |
| ROCK2 | Rho kinase isoform with similar roles. | Knockdown affects stress fiber formation. |
| DIAPH1 | Formin that nucleates actin filaments for stress fibers. | Negative regulators may inhibit its activity. |
| PFN1 | Profilin, actin-binding protein. | Modulates actin polymerization; overexpression can alter stress fibers. |
| CFL1 | Cofilin, actin depolymerizing factor. | Promotes actin turnover; can negatively regulate stress fiber assembly. |
| GSN | Gelsolin, actin severing protein. | Overexpression disassembles stress fibers. |
How Is negative regulation of stress fiber assembly Regulated?
Negative regulation of stress fiber assembly is controlled by multiple signaling pathways. Rho GTPase signaling is a central node: inhibition of RhoA or its effectors ROCK1/ROCK2 reduces stress fiber formation. Rac1 GTPase is required for stress fiber assembly, so negative regulators of Rac1, such as GTPase-activating proteins, can suppress assembly. G protein beta/gamma subunits can induce stress fiber formation in a Rho-dependent manner, and their inhibition negatively regulates assembly. Additionally, morphological reprogramming of primary cilia can mitigate fibrotic phenotypes by reducing stress fiber assembly, possibly through ciliary signaling that modulates Rho GTPase activity. Septins and class 18 myosins also contribute to the regulation of actin dynamics, with septins maintaining endothelial monolayer integrity and myosins influencing actin bundle organization. These pathways collectively ensure that stress fiber assembly is tightly controlled in response to mechanical and biochemical cues.
negative regulation of stress fiber assembly and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RHOA | Fibrosis, cancer | Knockout fibroblasts; overexpression of dominant-negative RhoA |
| RAC1 | Metastasis, cytoskeletal disorders | Rac1 knockout cells; point mutation (GTPase-deficient) |
| SEPT2 | Endothelial barrier dysfunction | Septin knockdown in endothelial cells |
| MYO18A | Sarcomeric and cytoskeletal diseases | Myo18A knockout; tagged knock-in for localization |
| CFL1 | Fibrosis, cancer invasion | Cofilin overexpression or knockout to modulate stress fibers |
Fibrosis
Fibrosis is characterized by excessive deposition of extracellular matrix and increased stress fiber assembly in fibroblasts and myofibroblasts. Negative regulation of stress fiber assembly is impaired in fibrotic conditions, leading to enhanced contractility and tissue stiffening. Morphological reprogramming of primary cilia length mitigates the fibrotic phenotype in fibroblasts across diverse fibrotic conditions, highlighting the therapeutic potential of targeting stress fiber assembly. Rho GTPase signaling is a key driver of fibrosis, and its inhibition reduces stress fiber formation and fibrotic markers.
Cancer and metastasis
Stress fibers are critical for cell migration and invasion, processes that are dysregulated in cancer. Rac1 GTPase, which is essential for stress fiber formation, is often overexpressed in cancers, promoting metastasis. Negative regulation of stress fiber assembly may suppress invasive behavior, making components of this process potential tumor suppressors. Targeting Rac1 or its downstream effectors to inhibit stress fiber assembly could be a therapeutic strategy in metastatic cancers.
Cytoskeletal and developmental disorders
Proper regulation of stress fiber assembly is essential for embryonic development and tissue morphogenesis. G protein beta/gamma subunits induce stress fiber formation in a Rho-dependent manner, and disruption of this signaling can lead to developmental defects. Septins and class 18 myosins are implicated in cytoskeletal organization, and mutations in these genes can cause disorders affecting cell shape and adhesion. Understanding negative regulation of stress fiber assembly provides insights into these conditions.
From negative regulation of stress fiber assembly-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate gene increase stress fiber assembly? | CRISPR knockout in fibroblasts, followed by phalloidin staining |
| Does a point mutation in RhoA affect its ability to regulate stress fibers? | CRISPR point mutation knock-in of constitutively active or inactive RhoA |
| How does a regulatory protein localize to stress fibers? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| Does overexpression of a negative regulator reduce fibrosis? | Overexpression of candidate gene in myofibroblasts, assess stress fibers and fibrotic markers |
| What genes are essential for negative regulation of stress fiber assembly? | Genome-wide CRISPR library screening with stress fiber readout |
| How does primary cilia length affect stress fiber assembly? | Knockout of ciliary genes or overexpression of ciliary proteins |
How to Study the negative regulation of stress fiber assembly Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Phalloidin staining + confocal microscopy | Stress fiber abundance and morphology | Quantify effects of gene knockout on stress fiber assembly |
| Live-cell imaging with GFP-actin | Dynamics of stress fiber assembly/disassembly | Real-time visualization of negative regulation |
| CRISPR knockout library screening | Genes whose loss alters stress fiber assembly | Identify negative regulators in fibroblasts |
| Phosphoproteomics | Signaling changes (e.g., RhoA/Rac1 activity) | Map pathways that inhibit stress fiber assembly |
| RNA-seq | Transcriptional profiles | Discover gene expression changes linked to GO:0051497 |
| Immunoprecipitation + mass spectrometry | Protein-protein interactions | Find novel stress fiber regulators |
| Primary cilia length measurement | Cilia morphology | Correlate cilia reprogramming with reduced stress fibers |
| Focal adhesion staining (vinculin, paxillin) | Focal adhesion assembly | Assess downstream effects of negative regulation |
Fluorescence microscopy and phalloidin staining
Fluorescence microscopy with phalloidin, which binds F-actin, is the gold standard for visualizing stress fibers. Researchers can quantify stress fiber number, length, and thickness in fibroblasts under different genetic conditions, such as Rac1 knockout or RhoA inhibition. Live-cell imaging with GFP-tagged actin or myosin allows dynamic assessment of stress fiber assembly and disassembly.
CRISPR-based genetic screens
Genome-wide CRISPR knockout or activation screens can identify genes whose loss or overexpression alters stress fiber assembly. Cells are infected with lentiviral sgRNA libraries, selected, and then stained for stress fibers; sgRNAs enriched in cells with reduced stress fibers point to negative regulators. This approach has been used to uncover Rac1 as critical for stress fiber formation.
Proteomics and phosphoproteomics
Mass spectrometry-based proteomics can identify proteins associated with stress fibers and their post-translational modifications. Phosphoproteomics reveals signaling changes, such as RhoA or Rac1 activity, that correlate with negative regulation of stress fiber assembly. Immunoprecipitation of stress fiber components followed by mass spectrometry can uncover novel interactors.
Transcriptomics and bioinformatics
RNA sequencing of fibroblasts under conditions that inhibit stress fiber assembly can reveal transcriptional programs downstream of negative regulation. Differential expression analysis of cumulus granulosa cells from patients with diminished ovarian reserve identified transcriptional changes that may affect cytoskeletal organization. Bioinformatics pathway enrichment can highlight GO terms like GO:0051497 in disease datasets.
How CRISPR Can Be Used to Study GO:0051497 negative regulation of stress fiber assembly
Knockout
CRISPR knockout of candidate negative regulators (e.g., RhoA, Rac1) can be used to test whether loss of function increases stress fiber assembly. For example, Rac1 knockout impairs stress fiber formation, confirming its positive role; knocking out a negative regulator would be expected to enhance assembly. Fibroblasts with knockout of genes like CFL1 or GSN can be generated to study their roles in stress fiber disassembly.
Point Mutation
CRISPR point mutation knock-in can create constitutively active or inactive versions of GTPases such as RhoA or Rac1 to dissect their roles in stress fiber assembly. For instance, a GTPase-deficient Rac1 mutant can be introduced to confirm that its activity is required for stress fiber formation. Point mutations in actin or actin-binding proteins can also reveal residues critical for negative regulation.
Knock-in
Knock-in of fluorescent tags (e.g., GFP, mCherry) at endogenous loci allows visualization of stress fiber-associated proteins in live cells. Tagged knock-in of Myo18A or septins can reveal their localization dynamics during negative regulation of stress fiber assembly. Additionally, knock-in of promoter-reporter constructs can monitor transcriptional changes in response to signals that inhibit stress fiber assembly.
Overexpression
Overexpression of candidate negative regulators (e.g., CFL1, GSN) can be achieved by CRISPR activation or lentiviral delivery to test whether increased levels reduce stress fiber assembly. Overexpression of primary cilia-related genes can reprogram cilia length and mitigate fibrosis, providing a model for negative regulation. Overexpression studies complement knockout approaches to establish causality.
How EDITGENE Supports negative regulation of stress fiber assembly Research
Researchers studying negative regulation of stress fiber assembly-related genes often need to determine whether a candidate gene is causally involved in this process or merely correlated with changes in actin cytoskeleton. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic manipulation in relevant cell models, from knockout to point mutation, knock-in, and overexpression, as well as high-throughput library screening and bioinformatics support.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of stress fiber assembly research.
Frequently Asked Questions About negative regulation of stress fiber assembly
What is negative regulation of stress fiber assembly?
It is any biological process that stops, prevents, or reduces the assembly of stress fibers, which are contractile bundles of actin microfilaments and associated proteins found in fibroblasts, as defined by GO:0051497.
What genes are involved in negative regulation of stress fiber assembly?
Key genes include RHOA, RAC1, GNAI, SEPT2, SEPT7, MYO18A, MYO18B, ACTB, ACTG1, VCL, PXN, ZYX, ROCK1, ROCK2, DIAPH1, PFN1, CFL1, and GSN, based on experimental evidence.
How is stress fiber assembly regulated?
Stress fiber assembly is regulated by Rho GTPase signaling, Rac1 activity, G protein beta/gamma subunits, septins, and class 18 myosins; negative regulation involves inhibiting these pathways.
What diseases are associated with dysregulated stress fiber assembly?
Fibrosis, cancer metastasis, and cytoskeletal disorders are linked to abnormal stress fiber assembly; negative regulation is impaired in fibrosis.
How can I study negative regulation of stress fiber assembly?
Use fluorescence microscopy with phalloidin, CRISPR knockout or overexpression of candidate genes, live-cell imaging, proteomics, and RNA-seq to assess stress fiber changes.
What is the role of Rho GTPase in stress fiber assembly?
Rho GTPase promotes stress fiber assembly by activating ROCK and downstream effectors; inhibiting Rho signaling negatively regulates assembly.
Does Rac1 promote or inhibit stress fiber assembly?
Rac1 promotes stress fiber formation and focal adhesion assembly; its deletion impairs stress fibers, so negative regulators of Rac1 inhibit assembly.
How does primary cilia affect stress fiber assembly?
Morphological reprogramming of primary cilia length mitigates fibrotic phenotypes and reduces stress fiber assembly in fibroblasts.
What experimental models are used to study GO:0051497?
CRISPR knockout, point mutation, knock-in, and overexpression cell models, combined with imaging and omics, are used to study negative regulation of stress fiber assembly.
Can CRISPR screening identify new regulators of stress fiber assembly?
Yes, genome-wide CRISPR knockout or activation screens coupled with stress fiber imaging can identify genes whose loss or gain alters assembly.
Conclusion
Negative regulation of stress fiber assembly (GO:0051497) is a critical biological process that controls actin cytoskeleton dynamics in fibroblasts and other cells. Dysregulation of this process contributes to fibrosis, cancer, and developmental disorders, making it a promising therapeutic target. By leveraging CRISPR-based models and advanced imaging, proteomics, and bioinformatics, researchers can uncover the molecular mechanisms that stop or reduce stress fiber assembly. EDITGENE provides end-to-end services to accelerate these discoveries.
References
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- 2. Anderson S et al.. 2004. Rho-mediated assembly of stress fibers is differentially regulated in corneal fibroblasts and myofibroblasts.. Exp Cell Res 298(2):574-83 PMID: 15265703
- 3. Kim J et al.. 2023. Septin and actin contributions to endothelial cell-cell junctions and monolayer integrity.. Cytoskeleton (Hoboken) 80(7-8):228-241 PMID: 36205643
- 4. Horsthemke M et al.. 2024. Are the class 18 myosins Myo18A and Myo18B specialist sarcomeric proteins?. Front Physiol 15:1401717 PMID: 38784114
- 5. Guo F et al.. 2006. Genetic deletion of Rac1 GTPase reveals its critical role in actin stress fiber formation and focal adhesion complex assembly.. J Biol Chem 281(27):18652-9 PMID: 16698790
- 7. Ueda H et al.. 2000. G protein betagamma subunits induce stress fiber formation and focal adhesion assembly in a Rho-dependent manner in HeLa cells.. J Biol Chem 275(3):2098-102 PMID: 10636914
- 8. Liu L et al.. 2022. Differential transcriptional profiles of human cumulus granulosa cells in patients with diminished ovarian reserve.. Arch Gynecol Obstet 305(6):1605-1614 PMID: 35024907
